The recent upgrade of the Advanced Photon Source has introduced the world’s brightest synchrotron x-ray source. The X-ray Science Division (XSD) at Argonne National Laboratory invites applications for a postdoctoral researcher position to develop novel coherent X-ray diDraction techniques for three-dimensional imaging of crystalline structure. The dominate eDort of the postdoctoral appointee will be to develop high fidelity simulations and/or algorithms to enable Bragg coherent diDraction imaging. We expect x-ray ptychography and coded aperture methods to play a fundamental role in creating a robust 3D imaging technique suitable across diverse scientific communities.

This project has two interconnected aims. The first is to create an accurate “digital twin” of the experiment through end-to-end simulation of x-rays involving their propagation through beamline optics, scattering from the sample, coded aperture, and ultimately their recording at the detector. This eDort will build on ongoing work at the APS, integrating x-ray optics and wave propagation models with realistic sample simulations based on dislocation dynamics and molecular dynamics of relevant materials. Significant attention needs to be invested in the simulation of diDraction, including both the interaction of the
beams with the samples and subsequent propagation to the detector through coded apertures or phase modulators.

The second aim of the project will use the digital twin to develop experimental methods and algorithms to enable robust phase retrieval of reciprocal space measurements to direct space images. These methods are expected to expand on recently demonstrated ideas using ptychography, coded apertures and phase masks, that capture and encode phase information in the measurement.

The successful candidate is expected to play a leading role in at least one of these two aims, as well as participate in the development of experiments to test the methods. The multi-disciplinary team in this project includes researchers from multiple groups within the X-ray Science Division, the Center for Nanoscale Materials and the Materials Science Division of Argonne.

Position Requirements

• Ph.D. in material science and engineering, physics, in Electrical Engineering and Computer Science or related field obtained within the last five years.

• Experience with X-ray physics or optical wave modeling.

• Proficiency in programming with Python.

• Exceptional communication skills, ability to communicate eDectively with internal and external collaborators and ability to work in team environment.

• Ability to model Argonne’s Core Values: Impact, Safety, Respect, Integrity, and Teamwork.

• Ability to understand, value, and promote diversity, equity, inclusion, and accessibility.

Preferred Knowledge, Skills, and Experience

• Experience with coherent diDraction imaging or x-ray microscopy methods.

• Knowledge of crystallography.

• Experience with molecular modeling of crystals, dislocation dynamics, and defect analysis, linking atomic-scale simulations to macroscopic properties.

• Familiarity or interest in machine learning methods and computing frameworks such as PyTorch and TensorFlow.

• Experience with high-performance computing and/or scientific workflow.

• Strong background in inverse problems, numerical optimization and image processing.

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